validate birthday to avoid mysql errors on invalid birthdays https://www.honeybadger.io/inspector/p/3240/3437722/52
fix MissingTemplate error for another bad crawler
remove from section should pretend to succeed when user has already been removed
actually just some comments
functionality for admin users to assume the identity of any other user
cr feedback from brendan
Merge pull request #367 from code-dot-org/assume-identity

Assume identity